A chemical admixture is a precise tool, and its result depends as much on how it is used as on its quality. These are the five mistakes we meet most on sites and at batching plants:
1. Dosing "by eye"
Overdosing a superplasticizer can cause segregation and bleeding, and with retarders it can delay set far more than intended. Underdosing simply fails to deliver. Stick to the dosage from the trial mix and the product datasheet.
2. Adding water on site to recover slump
The most expensive mistake. Every extra litre of water raises the water-cement ratio and lowers strength. If concrete loses workability, revisit the admixture type and dosage — not the water hose.
3. Ignoring cement compatibility
Cements differ in composition, and the same admixture can behave differently with another cement. When the cement source changes, repeat the trial.
4. Combining two admixtures without checking
Some admixtures do not work well together when added at the same time or pre-mixed. Ask your supplier before combining products.
5. Poor storage
Direct sun or open containers can change a product's properties. Store admixtures in the shade in sealed containers, and agitate drums before use where the datasheet says so.
Having slump or setting-time problems on site? EMOCON's technical team is ready to help.